In the story Misery, it would seem as if the narrator and the protagonis, Iona, are the same person but it is not. In fact, the narrator is a third person omniscient and subjective which knows all of Iona's feelings and narrates them from an emotional and cathartic point of view.
The subject of the story is the people's inhuman indifference to feel the pain of others. Throughout the story Iona is struggling with the grief of the death of his son. Already his life is miserable: He has to deal with mean customers, do repetitive work, and live in loneliness while grieving the loss of his son, which is painful enough! On top of that, he cannot find a single person to talk to about his grief. In the end of the story, he ends up finding nothing but a HORSE to talk to!
This is what shows that the point of view is from an outside narrator looking in the evil and meanness of a society that is not even able to support a man in need.